First of all, if you read the article, the US and EU have a long list of trade disputes and grievances to resolve themselves. It warms their hearts and improves the atmosphere just to talk about dealing with common threats, more specifically the state subsidies aka China. One particular common threat is China's ambition in civil aircraft manufacturing, with COMAC threatening both Boeing and Airbus in the intermediate term. It appears to be an area the US and EU can agree on. The problem is, Boeing and Airbus compete in the large Chinese aviation market, and COMAC does not pin its success on accessing to the US or EU markets, not initially anyway.
Second, WTO is a consensus-driven agreement. There is China in it and there are hundreds of other countries in it too. It's not IMF or World Bank where the US or EU wield veto power. You can negotiate and bargain the hell out of it there for many years. Meanwhile, China will continue to do what it does best, and that is growth.
The bottom line is, trade is a two-way street, particularly for big trading powers. You can't just dictate your rules on to other big players. The US going back to WTO is to take a step back and appeal to EU. The US had tried unilateral approach with Trump, it didn't work out well obviously. Before that, the US tried to work with "like-minded" friends and partners to rewrite the trading rules for the 21st century (otherwise known as containing China); supposedly it would be easier than going through WTO. That was embodied in TPP and TTIP. How did they fare?